How to Test

Last Updated: June 2026

To diagnose and determine disease stage of syphilis, diagnosis is by a combination of serology, PCR of lesions, past testing and treatment history and clinical assessment.

There are two types of syphilis testing.

Treponemal tests are specific to syphilis but only tell us if someone has ever had syphilis (including an old infection that has already been treated i.e.. Detected/Not Detected – Reactive or Non-Reactive).

Non-treponemal tests such as RPR and VDRL tell us how infectious the person is and how recent the infection is likely to be.

We use both types of testing to screen and diagnose syphilis.

Baseline Screening, Request	Further Information
Syphilis serology – Syphilis antibody	Laboratory to perform initial syphilis specific antibody (CMIA/EIA) testing and confirmatory testing if positive (TPPA/TPHA)* and RPR as a marker of disease activity and treatment response
Syphilis NAAT or PCR swab of lesion	Additional test if lesions present. Swab lesion. Must be accompanied by serology noting serology might return non-reactive if early syphilis however the PCR may return positive indicating treatment needed. If any anogenital or pharyngeal ulceration present, request ‘herpes PCR’ on the same swab, and collect a separate dry swab for ‘mpox NAAT’.
In addition, recommend comprehensive screening:
HIV Serology	Whenever testing for syphilis always test for HIV unless known HIV positive (refer to Australian STI Management Guidelines for Use in Primary Care – HIV)
Hepatitis B Serology	Unless not required (refer to Australian STI Management Guidelines for Use in Primary Care)
Hepatitis C Serology
Other STIs and BBVS	Refer to relevant population group guidelines for additional recommended tests.